I got my Diablosport Predator yesterday, so I was messing around with it today trying to get my speedometer to read accurately again. Is the speedometer on the dash programmed to read higher than actual speed? I had my GPS on the dash and when it showed 90km/h, my speedometer read ~92km/h and my SGII read 89km/h.

Driving home from work like this, my odometer said I drove 21.4km and my GPS said 21.0. Any ideas?

 

In my experience, the speedometer is usually about 2~3% higher than what the PCM sees. That's why the speedo does not exactly agree with the ScanGauge. If you want better accuracy, you can tweak the calibration to make the speedometer match the GPS.

 

when i plugged in my predator..and tuned it. i put in for tire size change but it pulled my axle ratio to a 4:10 and i didnt touch it. and i found that by accident and had to switch mine to 3:73..check that to see maybe tthats wrong?